BackgroundBecause very large numbers of single nucleotide polymorphisms (SNPs) are now available throughout the genome, they are particularly suitable for the detection of genomic regions where a reduction in heterozygosity has occurred and they offer new opportunities to improve the accuracy of inbreeding () estimates. Runs of homozygosity (ROH) are contiguous lengths of homozygous segments of the genome where the two haplotypes inherited from the parents are identical. Here, we investigated the occurrence and distribution of ROH using a medium-dense SNP panel to characterize autozygosity in 516 Valle del Belice sheep and to identify the genomic regions with high ROH frequencies.ResultsWe identified 11,629 ROH and all individuals displayed at least one ROH longer than 1 Mb. The mean value of estimated from ROH longer than1 Mb was 0.084 ± 0.061. ROH that were shorter than 10 Mb predominated. The highest and lowest coverages of Ovis aries chromosomes (OAR) by ROH were on OAR24 and OAR1, respectively. The number of ROH per chromosome length displayed a specific pattern, with higher values for the first three chromosomes. Both number of ROH and length of the genome covered by ROH varied considerably between animals. Two hundred and thirty-nine SNPs were considered as candidate markers that may be under directional selection and we identified 107 potential candidate genes. Six genomic regions located on six chromosomes, corresponding to ROH islands, are presented as hotspots of autozygosity, which frequently coincided with regions of medium recombination rate. According to the KEGG database, most of these genes were involved in multiple signaling and signal transduction pathways in a wide variety of cellular and biochemical processes. A genome scan revealed the presence of ROH islands in genomic regions that harbor candidate genes for selection in response to environmental stress and which underlie local adaptation.ConclusionsThese results suggest that natural selection has, at least partially, a role in shaping the genome of Valle del Belice sheep and that ROH in the ovine genome may help to detect genomic regions involved in the determinism of traits under selection.Electronic supplementary materialThe online version of this article (10.1186/s12711-017-0360-z) contains supplementary material, which is available to authorized users.

Summary 18The availability of dense single-nucleotide polymorphism (SNP) assays allows for the 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 F o r P e e r R e v i e wThe abundance of single-nucleotide polymorphisms (SNPs) throughout the genome and the 44 availability of dense SNP assays, makes these markers particularly suitable for the detection of 45 genomic regions where a reduction in heterozygosity occurred (Kim et al. 2013). Runs of 46 homozygosity (ROH) are contiguous segments of homozygous genotypes that are present in an 47 individual due to parents transmitting identical haplotypes to their offspring (Gibson et al. 2006). 48In animal genetics, ROH are used as predictors of whole genome inbreeding levels (Purfield et 49 al. 2012; Marras et al. 2015; Mastrangelo et al. 2016), to characterize the genomic distribution of 50 inbreeding depression on a phenotype (Biscarini et al. 2014; Pryce et al. 2014), and to identify 51 genes associated with traits of economic interest present in these regions (Zhang et al. 2015; 52 Szmatola et al. 2016; Purfield et al. 2017). Selection pressure and mating schemes can be 53 disentangled by ROH; therefore, ROH detection can also be used to minimize inbreeding and to 54 improve mating systems (Bosse et al. 2012; Zhang et al. 2015 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 Runs of homozygosity definition 106Runs of homozygosity were estimated for each animal using PLINK (Purcell et al. 2007). No where L ROH is the total length of all ROH in the genome of an individual, and L aut the specified 118 length of the autosomal genome covered by SNPs on the chip (2 452.06 Mb). 119Each ROH was categorized based on its physical length into 1 to <5 Mb, 5 to <10 Mb, 10 to <15 and averaging this per breed. 123The genomic inbreeding coefficient based on the difference between observed vs. expected 124 number of homozygous genotypes (F HOM ) was also estimated using PLINK (Purcell et al. 2007). 125Pearson's correlation between the two measures of inbreeding was calculated. 127Detection of common runs of homozygosity 128To identify the genomic regions most commonly associated with ROH for the meta-population, 129and for groups on the basis of production purposes (milk, meat, wool and "milk and meat"), the 136Genomic coordinates for all the identified ROH islands were used for the annotation of genes 137 that were fully or partially contained within each selected region using the UCSC Genome 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59...

Copy number variation (CNV) is a major source of genomic structural variation. The aim of this study was to detect genomic CNV regions (CNVR) in Valle del Belice dairy sheep population and to identify those affecting milk production traits. The GO analysis identified possible candidate genes and pathways related to the selected traits. We identified CNVs in 416 individuals genotyped using the Illumina OvineSNP50 BeadChip array. The CNV association using a correlation-trend test model was examined with the Golden Helix SVS 8.7.0 tool. Significant CNVs were detected when their adjusted p-value was <0.01 after false discovery rate (FDR) correction. We identified 7,208 CNVs, which gave 365 CNVRs after aggregating overlapping CNVs. Thirty-one CNVRs were significantly associated with one or more traits included in the analysis. All CNVRs, except those on OAR19, overlapped with quantitative trait loci (QTL), even if they were not directly related to the traits of interest. A total of 222 genes were annotated within the significantly associated CNVRs, most of which played important roles in biological processes related to milk production and health-related traits. Identification of the genes in the CNVRs associated with the studied traits will provide the basis for further investigation of their role in the metabolic pathways related to milk production and health traits.

The availability of genotyping assays has allowed the detailed evaluation of cattle genetic diversity worldwide. However, these comprehensive studies did not include some local European populations, including autochthonous Italian cattle. In this study, we assembled a large-scale, genome-wide dataset of single nucleotide polymorphisms scored in 3,283 individuals from 205 cattle populations worldwide to assess genome-wide autozygosity and understand better the genetic relationships among these populations. We prioritized European cattle, with a special focus on Italian breeds. Moderate differences in estimates of molecular inbreeding calculated from runs of homozygosity ( F ROH ) were observed among domesticated bovid populations from different geographic areas, except for Bali cattle. Our findings indicated that some Italian breeds show the highest estimates of levels of molecular inbreeding among the cattle populations assessed in this study. Patterns of genetic differentiation, shared ancestry, and phylogenetic analysis all suggested the occurrence of gene flow, particularly among populations originating from the same geographical area. For European cattle, we observed a distribution along three main directions, reflecting the known history and formation of the analyzed breeds. The Italian breeds are split into two main groups, based on their historical origin and degree of conservation of ancestral genomic components. The results pinpointed that also Sicilian breeds, much alike Podolian derived-breeds, in the past experienced a similar non-European influence, with African and indicine introgression.

This study demonstrates that in NCH aging individuals, MPS are associated with cortical and subcortical vascular and atrophic changes, and are probably, a warning sign of incipient cognitive decline. Subjects with MPS should manage rigorously cerebral SVD to prevent future physical and cognitive disabilities.